Abstract:
A total of 50 isolates of Rhizoctonia solani was isolated from infected roots and stem base of diseased
cotton seedlings collected from different locations throughout Bangladesh. Of them 29 were isolated from
samples of Hill cotton. Out of 29 samples of Hill cotton seedlings 16 were collected from 16 locations of
Bandarban district, 10 from 10 locations of Rangamati district and other three from 3 locations of Gazipur
district. Rest of 21 isolates were associated with samples of 4 American cotton varieties namely CB-3,
CB-5 and CB-9, CB-I a grown in the district of Gazipur, Dhaka, Rangpur, Pabna, Kushtia, Meherpur and
Natore. The isolates were designated with first letter of district names and first two letters of upzilla names
from where the diseased samples were collected along with a serial number. A series of experiments were
conducted for characterization of 50 isolates of R. solani associated with cotton grown in different
locations of Bangladesh. A total of 50 isolates of R. solani were found to infect the colton seedling.
Remarkable cultural and morphological variations were found among the isolates. Three types of
mycelium and colony structures viz compact, slightly fluffy or fluffy were observed. The colony color
was very light brown, light brown, brown and dark brown. Pattern of sclerotia distribution was throughout
the plate, at centre, periphery and irregular.
